Longitudinal Changes in Serum Markers of Bone Metabolism and Bone Material Strength in Premenopausal Women with Distal Radial Fracture.

BACKGROUND: Markers of bone metabolism (MBM) play an important role in fracture evaluation, and changes have been associated with increased fracture risk. The purpose of the present study was to describe changes in MBM in premenopausal women with distal radial fractures. METHODS: Premenopausal women with distal radial fractures (n = 34) and without fractures (controls) (n = 39) were recruited. Serum MBM in patients with distal radial fractures were obtained at the time of the initial presentation, 6 weeks, and 3, 6, and 12 months. MBM included 25(OH) vitamin D, PTH, osteocalcin, P1NP, BSAP, CTX, sclerostin, DKK1, periostin, and TRAP5b. Areal bone mineral density (aBMD) was assessed with dual x-ray absorptiometry, and the bone material strength index (BMSi) was assessed with microindentation. RESULTS: Most MBM reached peak levels at 6 weeks after the injury, including osteocalcin (+17.7%), sclerostin (+23.5%), and DKK1 (12.6%). Sclerostin was lower (-27.4%) and DKK1 was higher (+22.2%) at 1 year after the fracture. CTX declined below baseline levels at 6 and 12 months, whereas TRAP5b, BSAP, and periostin did not significantly change. At 12 months, sclerostin was lower (p = 0.003) and DKK1 was higher (p = 0.03) in the distal radial fracture group than in the control group. Greater fracture severity was associated with greater increases in P1NP and BSAP. aBMD and BMSi were not associated with fracture. CONCLUSIONS: Distal radial fractures caused increases in several MBM, which typically peaked at 6 weeks after injury and gradually decreased over 6 months. Sclerostin and DKK1 remained below and above baseline at 1 year, respectively. Increasing fracture severity resulted in larger changes in MBM. aBMD and BMSi did not discriminate between patients with distal radial fractures and controls. Continued efforts to identify markers of skeletal fragility in young women are warranted to mitigate future fracture risk. LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Association between forearm cortical bone properties and handgrip strength in women with distal radius fractures: A cross-sectional study.

OBJECTIVES: Mechanical and biochemical bone properties are influenced by muscles. However, the muscle-bone interaction has not been fully elucidated regarding the upper extremities. The objective of the present study was to evaluate the mechanical muscle-bone interaction at the forearm by evaluating the relationship between the properties of three-dimensional (3D) forearm cortical bone models derived from conventional computed tomography (CT) images and handgrip strength (HGS). METHODS: A total of 108 women (mean age, 75.2 ± 9.4 years; range, 62-101 years) with a distal radius fracture who took conventional CT scans for the assessment of the fracture were included in this study. Distal radius 3D models were reconstructed and the average cortical bone density (Cd) and thickness (Ct) of the region of interest (ROI), which might be affected by the forearm flexor muscles, were calculated using a 3D modeling software. Clinical parameters including HGS, lumbar and hip bone mineral densities (BMDs), and other demographic factors were also obtained. A multivariate linear regression analysis was performed to identify relevant factors associated with HGS. RESULTS: HGS was found to be independently associated with height and Cd, but no significant difference was found between HGS and Ct, age, weight, as well as lumber and hip BMDs. CONCLUSIONS: Cortical bone density might be associated with HGS, which is generated by the forearm flexor muscles. Hence, the mechanical muscle-bone interaction in the upper extremities could be supported by the present study.

Nanoscale perfluorocarbon expediates bone fracture healing through selectively activating osteoblastic differentiation and functions.

BACKGROUND AND RATIONALE: Fracture incidence increases with ageing and other contingencies. However, the strategy of accelerating fracture repair in clinical therapeutics remain a huge challenge due to its complexity and a long-lasting period. The emergence of nano-based drug delivery systems provides a highly efficient, targeted and controllable drug release at the diseased site. Thus far, fairly limited studies have been carried out using nanomedicines for the bone repair applications. Perfluorocarbon (PFC), FDA-approved clinical drug, is received increasing attention in nanomedicine due to its favorable chemical and biologic inertness, great biocompatibility, high oxygen affinity and serum-resistant capability. In the premise, the purpose of the current study is to prepare nano-sized PFC materials and to evaluate their advisable effects on promoting bone fracture repair. RESULTS: Our data unveiled that nano-PFC significantly enhanced the fracture repair in the rabbit model with radial fractures, as evidenced by increased soft callus formation, collagen synthesis and accumulation of beneficial cytokines (e.g., vascular endothelial growth factor (VEGF), matrix metalloprotein 9 (MMP-9) and osteocalcin). Mechanistic studies unraveled that nano-PFC functioned to target osteoblasts by stimulating their differentiation and activities in bone formation, leading to accelerated bone remodeling in the fractured zones. Otherwise, osteoclasts were not affected upon nano-PFC treatment, ruling out the potential target of nano-PFC on osteoclasts and their progenitors. CONCLUSIONS: These results suggest that nano-PFC provides a potential perspective for selectively targeting osteoblast cell and facilitating callus generation. This study opens up a new avenue for nano-PFC as a promising agent in therapeutics to shorten healing time in treating bone fracture.

Integrating 3D Printing and Biomimetic Mineralization for Personalized Enhanced Osteogenesis, Angiogenesis, and Osteointegration.

Titanium (Ti) alloy implants can repair bone defects at load-bearing sites. However, they mechanically mismatch with the natural bone and lack customized adaption with the irregularly major-sized load-bearing bone defects, resulting in the failure of implant fixation. Mineralized collagen (MC), a building block in bone, can induce angiogenesis and osteogenesis, and 3D printing technology can be employed to prepare scaffolds with an overall shape customized to the bone defect. Hence, we induced the formation of MC, made of hydroxyapatite (HAp) nanocrystals and collagen fibers, in 3D-printed porous Ti6Al4V (PT) scaffolds through in situ biomimetic mineralization. The resultant MC/PT scaffolds exhibited a bone-like Young's modulus and were customized to the anatomical contour of actual bone defects of rabbit model. We found that the biocompatibility and osteogenic differentiation are best when the mass ratio between HAp nanocrystals and collagen fibers is 1 in MC. We then implanted the MC/PT scaffolds into the customized radius defect rabbit model and found that the MC/PT scaffolds significantly improved the vascularized bone tissue formation and integration between new bone and the implants. Therefore, a combination of 3D printing and biomimetic mineralization could lead to customized 3D PT scaffolds for enhanced angiogenesis, osteogenesis, and osteointegration. Such scaffolds represent novel patient-specific implants for precisely repairing irregular major-sized load-bearing bone defects.

Prostate-Specific Membrane Antigen Expression in Distal Radius Fracture.

A 79-year old man with prostate cancer under active surveillance for 5 years was referred for a PSMA-PET/MRI for re-evaluation because of a rising prostate-specific antigen value. PET/MRI revealed a ribbonlike tracer accumulation in a healing fracture of the distal radius. This case illustrates that PSMA expression may occur in healing bone fractures in the distal radius. It can be assumed that benign causes of tracer accumulations in the upper extremities are missed in PET/CT due to elevated position of the arms during image acquisition.

The vitamin D receptor expression in skeletal muscle of women with distal radius fracture.

We evaluated the vitamin D receptor (VDR) expression in the forearm flexor muscle of women with distal radius fracture. High VDR expression was associated with low appendicular lean mass index. INTRODUCTION: We aimed to evaluate the relationship between the VDR expression in the muscle cell and the muscle mass in women with a distal radius fracture (DRF). METHODS: We prospectively recruited 45 women over 50 years of age (mean age, 66 years) with DRF and acquired biopsy of the forearm flexor muscle. The muscle cross-sectional area (CSA) and VDR expression were measured using immunohistochemistry staining. The clinical parameters including grip strength, gait speed, body mass index (BMI), bone mineral density (BMD), and serum vitamin D levels were compared between patients grouped by appendicular lean mass index and were correlated with the VDR expression. RESULTS: Twelve patients (27%) showed a decreased appendicular lean mass index, less than the cut-off value of 5.4 kg/m2 which was suggested by the Asian Working Group for Sarcopenia. Patients with a low appendicular lean mass index had significantly lower muscle CSA (p = 0.037), but a higher VDR expression (p = 0.045) than those with higher indices. VDR expression was negatively correlated with BMI (r = - 0.417, p = 0.004) and appendicular lean mass index (r = - 0.316, p = 0.044). CONCLUSIONS: DRF patients with low appendicular lean mass index presented high VDR expression and low CSA in forearm muscle cells. This suggests that the VDR expression might be upregulated in the attempt to compensate for the decreasing muscle mass. Further studies are necessary to explore the role of VDR in the progression of sarcopenia.

Bone Material Strength Index as Measured by Impact Microindentation in Postmenopausal Women With Distal Radius and Hip Fractures.

We tested whether cortical bone tissue properties assessed by in vivo impact microindentation would distinguish postmenopausal women with recent distal radius (DRF) or hip fracture (HF) from nonfracture controls (CONT). We enrolled postmenopausal women with recent DRF (n = 57), HF (n = 41), or CONT (n = 93), and used impact microindentation to assess bone material strength index (BMSi) at the anterior surface of the mid-tibia diaphysis. Areal bone mineral density (aBMD) (g/cm2 ) of the femoral neck (FN), total hip (TH), and lumbar spine (LS) were measured by dual-energy X-ray absorptiometry (DXA). HF and DRF subjects had significantly lower BMD than CONT at all sites (-5.6% to -8.2%, p < 0.001 for all). BMSi was 4% lower in DRF compared to CONT (74.36 ± 8.77 versus 77.41 ± 8.79, p = 0.04). BMSi was similarly lower in HF versus CONT, but the difference did not reach statistical significance (74.62 ± 8.47 versus 77.41 ± 8.79, p = 0.09). Lower BMSi was associated with increased risk of DRF (unadjusted OR, 1.43; 95% CI, 1.02 to 2.00, per SD decrease, p = 0.04), and remained statistically significant after adjustment for age, age and BMI, and age, BMI, and FN BMD (OR = 1.48 to 1.55). Lower BMSi tended to be associated with HF, but only reached borderline significance (unadjusted OR = 1.39; 95% CI, 0.96 to 2.01, p = 0.08). These results provide strong rationale for future investigations aimed at assessing whether BMSi can predict fracture in prospective studies and improve identification of women at risk for fragility fractures. © 2017 American Society for Bone and Mineral Research.

Cell-free scaffolds with different stiffness but same microstructure promote bone regeneration in rabbit large bone defect model.

To promote bone healing, bone repair biomaterials are increasingly designed to incorporate growth factors. However, the impact of matrix mechanics of cell-free scaffold independent of microstructure on the osteogenic differentiation of endogenous osteoprogenitor cells orchestrating bone repair and regeneration remains not to be fully understood. In our recent study, three-dimensional (3D) scaffolds with different stiffness but same microstructure have been successfully fabricated by coating decellularized bone with collagen/hydroxyapatite (HA) mixture with different collagen rations. It has been demonstrated that the scaffold with optimal stiffness can induce the osteogenic differentiation of MSCs in vitro and in the subcutaneous tissue. The present in vivo study further investigated the repair efficiency of these scaffolds in a rabbit radius with a critical-sized segmental defect model and its potential mechanism. Micro-computed tomography (µ-CT), X-ray and histological analysis were carried out to evaluate the repair capacity of these scaffolds. The results demonstrated that the cell-free scaffold with optimal stiffness incorporation of endogenous osteoprogenitor cells significantly promoted the repair and reconstruction quality of mass bone defect. One of the crucial mechanisms was that hypoxia and stromal cell-derived factor-1α (SDF-1α) mediated mesenchymal stem cells (MSCs) migration by which matrix mechanics exerted influence on bone fracture healing. These findings suggested that only modulating the matrix stiffness of cell-free scaffold can be one of the most attractive strategies for promoting the progression of bone healing.

Fracture Repair in the Distal Radius in Postmenopausal Women: A Follow-Up 2 Years Postfracture Using HRpQCT.

Fracture healing is characterized by an intense increase in modeling and remodeling of bone, which allows removal of the cast after a stable distal radius fracture within 3 to 5 weeks. However, at that time, bone strength has not recovered yet. We studied the changes in bone mineral density (BMD), microarchitecture, and bone stiffness after a distal radius fracture during a 2-year follow-up in comparison to the contralateral side and the association between the 2-year stiffness and baseline BMD, microarchitecture, and early changes in these parameters. The fractured side of 14 postmenopausal women (mean age 64 ± 8 years) with a conservatively treated distal radius fracture was scanned by high-resolution peripheral quantitative computed tomography (HRpQCT) at 1 to 2, 3 to 4, 6 to 8, and 12 weeks and 2 years postfracture. The same region contralaterally was scanned as well at the 2-year visit. BMD, microarchitecture, and stiffness parameters were determined and the fracture side was compared with the contralateral side using a linear mixed-effect model. Spearman's correlation was used to correlate the 2-year bone stiffness with baseline BMD, microarchitecture, and early 3-month changes in these parameters. Two years postfracture, cortical and trabecular thickness and torsional and bending stiffness were significantly higher at the fractured side compared with the nonfractured side (21%, 55%, 31%, and 29%, respectively, p < 0.05), whereas BMD was similar. Two-year torsional and bending stiffness correlated significantly with baseline BMD and cortical perimeter (|rho| ≥ 0.63, p < 0.016) but not with early changes in bone parameters. Using HRpQCT, this study illustrates that fracture healing is not completed by the time the cast is removed. We showed that from 6 weeks to 2 years postfracture, large changes occur in BMD, microarchitecture, and biomechanical parameters at the fractured side, which were fully recovered after 2 years in comparison to the nonfractured contralateral side. Interestingly, higher 2-year torsional and bending stiffness were associated with lower BMD and higher cortical perimeter at baseline. © 2015 American Society for Bone and Mineral Research.

Prevalence of Low Bone Mineral Density in Younger Versus Older Women With Distal Radius Fractures.

Although distal radius fractures (DRFs) are the most common fractures among younger women, few studies have examined bone health in this age group. We compared bone mineral density (BMD) of younger women (35-50 years) and older women (>50 years) treated for DRFs. Between January 2005 and August 2010, our orthopedic service obtained dual-energy x-ray absorptiometry scans from 128 women with DRFs (47 were 35-50 years old; 81 were older than 50 years). According to the World Health Organization classification system, 43% of the younger patients were osteopenic, and 6% were osteoporotic. Mean femoral neck BMD was 0.91 for the younger group and 0.80 for the older group (P < .05); t scores were -0.87 and -1.65, respectively (P < .05). The difference in femoral neck z scores between the younger and older patients was not statistically different: -0.69 and -0.67, respectively (P = .92). A notable proportion of younger patients with DRFs have osteopenia or osteoporosis. The similarity in z scores among younger and older women with DRFs and among patient groups differentiated by mechanism of injury suggests that any younger or older woman with a DRF should have her BMD evaluated and treated as appropriate.

Thermal changes during healing of distal radius fractures-Preliminary findings.

INTRODUCTION: The bone healing process is very complex. In simple terms, bone healing comprises three basic steps, the inflammation phase, the repair phase and the remodelling phase. The increase in blood flow around the fracture during the healing process increases the temperature of the surrounding tissue. Infrared thermography is a method of measuring body temperature that can detect temperature changes during bone healing. Studies on the application of thermography in traumatology are scarce, and there are no studies of thermal changes during normal bone healing. The authors have tried to determine the dynamics of thermal changes during bone healing. MATERIAL AND METHODS: The Flir ThermaCam B2 (FLIR Systems, Inc., Oregon, USA) was used for all measurements. Thermographic recordings were made one, three, five, 11 and 23 weeks after fracture. The contralateral, healthy, forearm was used for comparison. RESULTS: A total of 25 patients of mean age 65.9±10.4 years (range 50-80 years) with fracture of the distal radius were examined in this study. The mean temperature difference between healthy and fractured distal forearm one week after fracture was 1.20±0.48°C, three weeks after fracture was 1.42±0.54°C, five weeks after fracture was 1.04±0.53°C, 11 weeks after fracture was 0.50±0.30°C, and 23 weeks after fracture was 0.22±0.25°C. CONCLUSION: Preliminary findings during this research showed significant temperature changes during healing of distal radius fractures. Infrared thermography is a simple and reliable method in clinical practice that could be used as a good follow-up method in traumatology, but further investigations on more patients are needed.

Citrate-based biphasic scaffolds for the repair of large segmental bone defects.

Attempts to replicate native tissue architecture have led to the design of biomimetic scaffolds focused on improving functionality. In this study, biomimetic citrate-based poly (octanediol citrate)-click-hydroxyapatite (POC-Click-HA) scaffolds were developed to simultaneously replicate the compositional and architectural properties of native bone tissue while providing immediate structural support for large segmental defects following implantation. Biphasic scaffolds were fabricated with 70% internal phase porosity and various external phase porosities (between 5 and 50%) to mimic the bimodal distribution of cancellous and cortical bone, respectively. Biphasic POC-Click-HA scaffolds displayed compressive strengths up to 37.45 ± 3.83 MPa, which could be controlled through the external phase porosity. The biphasic scaffolds were also evaluated in vivo for the repair of 10-mm long segmental radial defects in rabbits and compared to scaffolds of uniform porosity as well as autologous bone grafts after 5, 10, and 15 weeks of implantation. The results showed that all POC-Click-HA scaffolds exhibited good biocompatibility and extensive osteointegration with host bone tissue. Biphasic scaffolds significantly enhanced new bone formation with higher bone densities in the initial stages after implantation. Biomechanical and histomorphometric analysis supported a similar outcome with biphasic scaffolds providing increased compression strength, interfacial bone ingrowth, and periosteal remodeling in early time points, but were comparable to all experimental groups after 15 weeks. These results confirm the ability of biphasic scaffold architectures to restore bone tissue and physiological functions in the early stages of recovery, and the potential of citrate-based biomaterials in orthopedic applications.

Superior angiogenic potential of GDF-5 and GDF-5(V453/V456) compared with BMP-2 in a rabbit long-bone defect model.

BACKGROUND: The clinical application of bone morphogenetic proteins such as BMP-2 and GDF-5 (growth and differentiation factor-5) may improve the outcome of bone defect repair. In addition to the osteoinductivity of BMPs, their angiogenic potential is important as an adequate blood supply is a prerequisite for bone-healing. We used a rabbit long-bone defect model to investigate whether angiogenicity and osteogenicity were correlated features of a BMP molecule by comparing the induction of blood vessel and bone formation by BMP-2, GDF-5, and a previously created swap mutant GDF-5V453/V456 (BB-1) with elevated BMP receptor-IA binding. METHODS: Microcomputed tomography and immunohistochemistry were used to assess early bone formation and neovascularization in 15-mm (critical-sized) rabbit radius defects treated with a growth factor-loaded collagen carrier. RESULTS: Blood vessel volume and surface area on days 7 and 14 after surgery were significantly greater in defects treated with GDF-5 and with BB-1 compared with controls (p < 0.05); BMP-2 enhanced vascularization on day 14 (p < 0.05). Cumulative data including both time points reflected increased vessel volume, intersection surface area, and number of vessels after treatment with GDF-5 and BB-1 compared with BMP-2 (p < 0.05), corresponding to the histology results. Each of the growth factors resulted in enhanced bone formation compared with controls on day 14 (p < 0.01), with BB-1 resulting in significantly more bone compared with GDF-5 as indicated by bone volume and surface area (p = 0.006). CONCLUSIONS: Both GDF-5 and BB-1 had high angiogenicity, and BB-1 outperformed GDF-5 with respect to osteogenicity. Strong induction of bone formation by BMP-2 and BB-1 was thus associated with BMP receptor-IA-dependent signaling, whereas the vascularization outcome was not. CLINICAL RELEVANCE: Although both BMP-2 and the GDF-5 variant BB-1 are good inducers of bone formation, BB-1 is especially promising for long-bone healing if high angiogenicity is desired along with high osteogenicity to promote recreation of optimal bone architecture.

[Nerve growth factor modulates bone morphogenetic protein expression in rabbit fracture].

OBJECTIVE: To explore the regulation of the expression of bone morphogenetic protein (BMP) of nerve growth factor (NGF) and examine the mechanism of nerve growth factor in promoting fracture repair. METHODS: A total of 108 healthy New Zealand white rabbits, weighting 2.5-3.0 kg, male or female, were randomly divided into 3 groups of NGF (Group A), antagonistic NGF (Group B) and control (Group C) (n = 36 each). A standard model of right mid-piece radial fracture was established. Group A received an intravenous injection of NGF 200 ng/kg twice daily 1 week while group B an intraperitoneal injection of NGF antibody 400 ng thrice daily for 3 weeks; group C physiological saline 1 ml twice daily for 3 weeks. And 6 rabbits in each group were sacrificed at 24 h, 48 h, 1 week, 3 weeks, 6 weeks and 8 weeks respectively. And BMP proteins of fracture specimens were analyzed by Western immunoblot. RESULTS: NGF promoted the expression of BMP in fracture while NGF antagonist inhibited its expression. NGF group produced more BMP earlier than control or NGF antagonist group during fracture healing while the production of BMP was more pronounced in control group than that in NGF antagonist group during fracture healing. And the differences were statistically significant (P < 0.05). CONCLUSION: Capable of promoting the expression of BMP in radial fracture of rabbit, NGF may be beneficial to fracture healing directly or indirectly.

Fracture during intravenous bisphosphonate treatment in a child with osteogenesis imperfecta: an argument for a more frequent, low-dose treatment regimen.

BACKGROUND/AIMS: Intravenous bisphosphonate therapy is the mainstay of medical treatment in osteogenesis imperfecta (OI) and has been shown to increase bone mass, decrease bone pain, improve mobility, and reduce the incidence of fractures. Sclerotic metaphyseal lines parallel to the growth plate are seen on long bone radiographs following cyclical intravenous therapy. These areas create stress risers within the bone that may act as foci for subsequent fractures as exemplified in this clinical case. METHODS: An 8-year-old girl with OI sustained a distal radial fracture following 3 years of treatment with 6-monthly intravenous zoledronate. Her diagnosis, response to treatment, and subsequent fracture at a sclerotic metaphyseal line is described. RESULTS: Peripheral quantitative computer tomography was used to characterise the presence of multiple stress risers at the distal forearm. Trabecular bone mineral density fluctuated from 34 to 126% compared to neighbouring 2-mm regions. CONCLUSION: There remain many unanswered questions about optimal bisphosphonate treatment regimens in children with OI. The formation of stress risers following intravenous bisphosphonate treatment raises the hypothesis that a more frequent and low-dose bisphosphonate regimen would provide more uniform dosing of bone in the growing child and reduce the likelihood of fractures compared to current treatment practices.

[Promotion effect of nuclear factor kappa B p65 on early fracture healing of rat radius by elevating prostaglandins E2 production and regulating inhibitor of DNA binding 2 protein expression].

OBJECTIVE: Series of complicated molecule signal pathway are involved in the bone regeneration. To explore the possibility of nuclear factor kappa B (NF-kappaB) which is taken as the "key activation" during the fracture healing and provide the laboratory evidence for the gene therapy of nonunion or delayed union of fractures. METHODS: Thirty-three adult male Wistar rats (weighing 180-220 g) were selected and divided randomly into 4 groups: group A (the control group, n=3), the rigth lower segments of radius were injected with normal saline 0.3 mL for 7 days, once per day; group B (Bay 11-7082 injection group, n=6), the middle and distal radius were injected with normal saline containing 50 pmol/L NF-kappaB inhibitor Bay 11-7082 0.3 mL for 7 days, once per day; group C (fracture group, n=12), the right middle and distal radius were cut by a sharp scissors to form per fracture model; and group D (Bay 11-7082 treatment group, n=12), based on group C, 0.3 mL of 50 micromol/L Bay 11-7082 were injected into the fracture site for 7 days, once per day. The callus tissues were harvested at 3, 7, 14, and 28 days after fracture for Western blot analysis, alkaline phosphatase (ALP) activity assessment, prostaglandins E2 (PGE2) production assay, and histological observation. RESULTS: The rats of all groups were survival till the experiment completion. At 3 and 7 days after injection, there was no significant difference in the ALP activity and PGE2 production between group B and group A (P > 0.05); but group C was significantly higher than group A (P < 0.01) and group D was significantly lower than group A (P < 0.01). The expressions of NF-kappaB p65, bone morphogenetic protein 7 (BMP-7), and inhibitor of DNA binding 2 (Id2) were observed at fracture sites of 4 groups. There was no significant difference in the expressions of NF-kappaB p65, BMP-7, and Id2 between group B and group A (P > 0.05); the expressions of NF-kappaB p65 and BMP-7 were significantly higher and the expression of Id2 was significantly lower in group C than group A (P < 0.01); and the expressions of NF-kappaB p65 and BMP-7 were significantly lower and the expression of Id2 was significantly higher in group D than group A (P < 0.01). The histological observation showed that a lot of osseous callus formed in group C at 14 and 28 days. CONCLUSION: but osseous callus just began to form in group D at 28 days. NF-kappaB p65 can facilitate early fracture healing of rat radius by elevating the PGE2 production and regulating BMP-7 and Id2 expression.

Rapid remineralization of the distal radius after forearm fracture in children.

BACKGROUND: Bone mineral content (BMC) and density (BMD) have been shown to diminish after fracture and immobilization in adults. Distal radius fractures are common in children, and unlike adults, there is a low incidence of refracture. The primary aim of this study was to assess the change in radial BMC and BMD after upper extremity fracture and casting in healthy pediatric patients. METHODS: Patients were recruited at the time of distal radius fractures casting. The nonfractured (non-Fx) distal radius was initially scanned by dual energy x-ray absorptiometry (baseline), and then both arms were scanned at the time of cast removal (CastOff), and 4, 8, 12, 24, and 52 weeks post CastOff. RESULTS: Twenty-one patients were enrolled (13 male, 13 Caucasian; 10.4±2.5 y) with an average length of casting of 38±11 days. Eighteen patients (86%) completed all protocol requirements. At CastOff, there was no significant difference in total BMC or BMD between the Fx and non-Fx arms. From CastOff to 24 weeks, the overall change in BMC and BMD for the non-Fx arm was +4.2% and +0.2%, respectively, whereas for the Fx arm, the change was +8.3% and +3.4%, respectively. By 24 weeks, the difference in the overall change in BMD between the Fx and non-Fx arms was statistically significant (greater than instrumental error; P<0.05). However, by 52 weeks, these differences were no longer significant. The increased mineralization was unrelated to age, sex, arm dominance, or calcium intake. CONCLUSIONS: These data show that there is rapid remineralization after a simple forearm fracture in children, with a transient elevation in BMD in the Fx arm after casting. This novel finding suggests that bone may be stronger around the site of fracture and could significantly change how we counsel young patients recovering from forearm fracture. Future research should focus on children immobilized for varying lengths of time and those with repeat fractures, using volumetric techniques of bone geometry and strength assessment. CASE SERIES: Therapeutic Studies-investigating the results of treatment, Level IV.

[Expression of vascular endothelial growth factor and microvessel density in rabbit radius defects repaired with allogeneic and autogenic bone].

OBJECTIVE: To investigate the expression levels and significance of vascular endothelial growth factor (VEGF) and microvessel density (MVD) in rabbit radius defects repaired with allogeneic and autogenic bone. METHODS: Forty adult New Zealand rabbits were chosen, and 10 mm bone defect model was created in the bilateral radii of 28 experimental rabbits. The other 12 rabbits provided allogeneic bone under the standard of American Association of Tissue Bank. In the left side, allogeneic bone were used to repair bone defect (experimental group), equal capacity autogenous iliac bone was used in the right side (control group). Animals were sacrificed at 2, 4, 8, and 12 weeks postoperatively. Immunohistochemical method was used to determine the expression of VEGF, CD34 protein and MVD counting. Bone histomorphometric parameters, including percent trabecular area (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), and trabecular separation (Tb.Sp) were measured by von Kossa staining undecalcified slices. The relation was analyzed between VEGF and MVD, histomorphometric parameters. RESULTS: The positive signals of VEGF protein were detected in cytoplasm of vascular endothelial cells, chondrocytes, osteoblasts, fibroblasts and osteoclasts. At 2 weeks, there was no significant difference in VEGF protein expression between experimental group and control group (P > 0.05); at 4 and 8 weeks, the expression of VEGF in control group was significantly higher than that in experimental group (P < 0.05); and at 12 weeks, there was no significant difference between two groups (P > 0.05). There was a positive correlation (P < 0.01) between VEGF expression and MVD value in two groups at 2, 4, 8, and 12 weeks postoperatively. There was no significant difference in bone histomorphometric parameters (BV/TV, Tb.Th, Tb.N, Tb.Sp) between two groups at 12 weeks postoperatively (P > 0.05), but there was a positive correlation between VEGF expression and parameters of BV/TV, Tb.Th, and Tb.N (P < 0.01); and a negative correlation between VEGF and Tb.Sp (P < 0.01). CONCLUSION: VEGF can express diversity at different time and positions, and the different expressions indicated various biology significances in the process of the bone healing. It can coordinate growth of cartilage and bone and profit vascular reconstruction of allogeneic bone. VEGF may participate in promoting osteogenesis in the course of allogeneic bone transplantation.

The effect of zymosan and the protective effect of various antioxidants on fracture healing in rats.

AIM: To investigate the effects of free oxygen radicals and various antioxidants on bone healing after experimental formation of fracture. MATERIALS AND METHODS: Fifty male rats were used and divided into five groups (ten rats in each). The right forelimbs of the rats were broken by bimanual compression method. One hour before this procedure, 5 ml/kg of intraperitoneal (i.p.) physiologic saline were given to the control Group 1. All 40 rats in the experimental Groups 2, 3, 4 and 5 were treated with i.p. zymosan at a dosage of 100 mg/kg to induce the production of free radicals by stimulating NADPH oxidase in polymorphonuclear leukocytes. Zymosan induction was stopped on the fifth post-fracture day. In addition to the zymosan, i.p. 1 g/kg/day of dimethyl sulfoxide were given to the animals in Group 3, 50 mg/kg/d of Ginko biloba Extract (EGb 761) in Group 4 and 500 mg/kg/day of vitamin C in Group 5. Radiographs of the fractures of all animals were obtained to assess callus formation, remodeling and bridging bone formation under ether anesthetics on postfracture day 7, 14 and 21. All rats were euthanized on day 22, and sections of the radius and ulna were examined both histologically with light and electron microscopy and ultrastructurally. Statistical analysis was made with Kruskal-Wallis variance analyze test and comparison between groups was performed by Dunn's multiple comparison test. RESULTS: An impairment of bone healing was observed in Group 2 inducted with purely zymosan. Variable results were obtained for bone healing in the groups treated with various antioxidants. There was very significant difference of fracture healing between Groups 1 and 2 both histologically and radiologically (P < 0.001). There was significant difference between Groups 2 and 5 radiologically (P < 0.05). CONCLUSION: Free oxygen radicals demonstrate a negative effect on fracture healing and vitamin C (an antioxidant) partially prevents the negative effect of zymosan on fracture healing.

Tracking expression of virally mediated BMP-2 in gene therapy for bone repair.

Ex vivo gene therapy using stem cells transduced with viral vectors is a useful method for delivering a therapeutic protein to augment bone repair in animal models. However, the duration of cell-mediated protein production and the fate of the transduced cells are unknown. We constructed an adenoviral vector encoding Myc epitope tagged bone morphogenetic protein (BMP)-2 gene (AdBMP-2). Rat bone marrow cells transduced with this vector produced biologically active BMP-2 protein, which was confirmed by Western blot analysis and alkaline phosphatase assay. Implantation of bone marrow cells infected ex vivo with AdBMP-2 caused orthotopic bone formation in mouse hindlimbs and bony union of critical-sized mouse radial defects. Immunohistochemical analysis revealed that rBMCs expressed Myc epitope-tagged BMP-2 protein for 14 days in vivo and became incorporated in the endochondral fracture callus. This novel adenovirus encoding for epitope-tagged BMP-2 can be used for immunohistochemical tracking of transduced cells in ex vivo gene therapy for bone repair.